( 170 ) 
Globe, they ftand in the greater Half-'Circuit of the 
fame. 
So I have faid, with M^tius^ to put before me all the 
Eyes, v^herewith a Beetle is endued, th^t as Two and 
Twenty is to Seven, fo is the Quadrat Number of the 
Circle, to the Superficies. 
This being fo, comes out Three Thoufand One Hun- 
dred Eighty One Eyes, that are on both the Tunica Cor- 
nea of a Beetle ; if, as I have faid heretofore, they both 
make up a whole Globe. 
I have thought good to let a Defigner draw a Part of the 
Tunica Cornea of a Beetle, fo far as he could follow ic by 
the Help of the Magnifying Glafs, partly, to (hew the 
Multitude cf Eyes that ftand upon it ; and chiefly, to 
fliew that every one of them has a Convexity. 
But we m-wifl: not conceive, that every convex Sight of 
the Beetle^ has a Globical Roundnefij for if it w^as fb, 
he could not fee the Oljeds that were fomewhat diftant 
from him (I (peak here againft thefe that have difcovered 
fome Knowledge in the Art of Opticks) but they each 
of them, a flat kind of Convexity or Roundneft. 
When I told this to the Defigner, he did compare the(e 
flat Convexities," to the Buttons we wear in thefe Days, 
that are faid to be made of Prince Roiert*$ Mettal. 
I. A.B.C.D.E.F. doth fliew a part of the Tunica 
Cornea of a Beetle. 
ABC. doth (hew that part of it that is united'to the 
Head of the Beetle. 
DEFA. is very near to that part of the great Circle 
of the Superficies of the Cornea^ whereon I numbered 
Sixty Faces or Eyes from DEF to A; and between thefe 
Letters we come to fee, how each Face or Eye is Ele- 
vated into a Roundnefs, 
I 
